What exactly is a pentatonic scale?

A scale consisting of five tones. It is mostly used in the mode of national music. Such as do, re, mi, sol, la, (do). Chinese traditional music is based on China's pentatonic scale, whose names are Gong, Shang, Zheng and Yu respectively. "Harmony, division, b, tardiness and fairness" were used in the Tang Dynasty.

China's traditional musical scale has five basic tones, namely 12356, namely, common, upper, cross, positive and Yu. China's pentatonic scale doesn't have 4 and 7? So there is no small interval, but from these five basic scales, we can expand the mode by adding some inflections. The basic mode composed of these five notes and the high note 1 is called Gongdiao.

Extended data:

Usually, the music we know consists of seven notes, which are called "C, D, E, F, G, A, B" by fixed sound names, "1, 2, 3, 4, 5, 6, 7" by notation, and "do, re, mi, fa, 7" by volume names.

The fifth octave of the seventh scale plus five semitones becomes the scale of 12, and the pentatonic scale is more commonly used in China traditional folk music. Although it only uses five notes, it has a unique charm.

The pentatonic scale is characterized by no semitone (second degree), which is called "pentatonic scale without semitone" or "pentatonic scale with whole tone" in detail. Widely popular in Asia, Africa, some islands in the central Pacific, Hungary and Scotland, and native American tribes before Europeans arrived in America. Often referred to as the "China scale".

References:

Baidu encyclopedia-pentatonic scale